Among factors that can affect calf health, microbial quality of the pen air is poorly studied. In 25 Italian dairy farms, data concerning air quality in the calf pens, hygiene of pens and equipment, microclimatic conditions, calf health and management were collected during the winter season (January-March 2020 and December-March 2021). The average air Standard Plate Count (SPC) of 85 pens was 4.51 (SD = 0.52) log10 cfu/m3 whereas the average air ammonia concentration was 0.66 (SD = 0.53) ppm. Positive correlations were found between average Temperature Humidity Index (THI) in the pen and air SPC, night maximum THI and air SPC and between SPC and yeast, mould and ammonia concentration in the pen air. The concentrations of E. coli, Enterobacteriaceae and yeasts in the pen air were higher and calf cough increased as the renewal interval of bedding material became longer. High bedding dry matter and low THI were associated with low air SPC, good calf health scores and low mortality. Maintaining low bedding humidity and controlling microclimatic conditions can contribute to enhancing air microbiological quality in the pen and reduce calf diseases and mortality.

The aim of this study was testing a bacteriocin product for udder disinfection during milking. The herd was divided in two groups: treatment (T) and control (C). Sterile milk was collected from every single quarter during 3 months. At each sampling, an operator evaluated animal hygiene and teat apex conditions. The results of cyto-bacteriological analyses showed similar bacterial frequencies as well as somatic cells counts in the two groups, despite of the poor hygiene conditions of the herd. Therefore, given the results, the tested product resulted comparable to the conventional one to ensure udder health. Further studies are needed to confirm these results.